Graduate School of Science, Department of Chemistry, Kyoto University , Kyoto 606-8502, Japan.
Dipartimento di Scienza dei Materiali, Universitá di Milano Bicocca , via R. Cozzi 55, Milano 20125, Italy.
J Am Chem Soc. 2018 Jan 31;140(4):1415-1422. doi: 10.1021/jacs.7b11061. Epub 2018 Jan 22.
Heterogeneous photocatalysis is vital in solving energy and environmental issues that this society is confronted with. Although photocatalysts are often operated in the presence of water, it has not been yet clarified how the interaction with water itself affects charge dynamics in photocatalysts. Using water-coverage-controlled steady and transient infrared absorption spectroscopy and large-model (∼800 atoms) ab initio calculations, we clarify that water enhances hole trapping at the surface of TiO nanospheres but not of well-faceted nanoparticles. This water-assisted effect unique to the nanospheres originates from water adsorption as a ligand at a low-coordinated Ti-OH site or through robust hydrogen bonding directly to the terminal OH at the highly curved nanosphere surface. Thus, the interaction with water at the surface of nanospheres can promote photocatalytic reactions of both oxidation and reduction by elongating photogenerated carrier lifetimes. This morphology-dependent water-assisted effect provides a novel and rational basis for designing and engineering nanophotocatalyst morphology to improve photocatalytic performances.
非均相光催化对于解决当前社会所面临的能源和环境问题至关重要。尽管光催化剂通常在水存在的情况下进行操作，但水本身如何影响光催化剂中的电荷动力学仍不清楚。我们利用水覆盖控制的稳态和瞬态红外吸收光谱以及大模型（约 800 个原子）从头计算，阐明了水增强了 TiO 纳米球表面的空穴捕获，但对具有良好面的纳米颗粒没有增强。这种纳米球特有的水辅助效应源于水以配体的形式吸附在低配位 Ti-OH 位点上，或者通过与高度弯曲的纳米球表面上的末端 OH 之间的强氢键直接吸附。因此，纳米球表面与水的相互作用可以通过延长光生载流子的寿命来促进氧化和还原的光催化反应。这种形态依赖性的水辅助效应为设计和工程纳米光催化剂形态以提高光催化性能提供了新的合理基础。
